Systems and methods for reducing interference between a plurality of wireless communications modules

ABSTRACT

A wireless communications includes a first wireless communications and a second wireless communications. The first wireless communications module transmits or receives a first wireless signal in a first frequency band selected from a first frequency range. The second wireless communications module transmits or receives a second wireless signal in a second frequency band selected from a second frequency range, and adjusts a transmission power of the second wireless signal in response to that a frequency offset between the first frequency band and the second frequency band falls within a predetermined range. The first wireless communications module is further configured to determine an in-band range in the overlapping part of the first and second frequency ranges, and a transmission power of the second wireless signal is adjusted in response to a frequency offset between the first frequency band and the second frequency band.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of pending U.S. patent applicationSer. No. 12/829,943, filed on Jul. 2, 2010, which claims the benefit ofU.S. Provisional Application No. 61/224,107, filed on Jul. 9, 2009, theentirety of which is incorporated by reference herein; and U.S.Provisional Application No. 61/298,627, filed on Jan. 27, 2010, theentirety of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to the coexistence between a pluralityof wireless communications modules, and more particularly, to systemsand methods for the reducing interference between a plurality ofco-existed wireless communications modules.

2. Description of the Related Art

To an increasing extent, a multitude of communication functions arebeing merged into mobile devices. As shown in FIG. 1, a cellular phonemay connect to a wireless local area network (WLAN) via a WirelessFidelity (WiFi) module thereof and simultaneously communicate with aBluetooth (BT) handset (or a Bluetooth car audio, or others) through aBluetooth module thereof. A WLAN system is typically implemented insidebuildings as an extension to wired local area networks (LANs) and isable to provide the last few meters of connectivity between a wirednetwork and mobile or fixed devices. According to the IEEE 802.11standard, most WLAN systems may operate in the 2.4 GHz license-freefrequency band and have very low throughput rates because of thecoexistence interference from BT. Referring to FIG. 1, a WLAN isestablished by an access point (AP) connecting to a LAN by an Ethernetcable. The AP typically receives, buffers, and transmits data betweenthe WLAN and the wired network infrastructure. The AP may support, onaverage, twenty devices and have a coverage varying from 20 meters in anarea with obstacles (walls, stairways, elevators etc) to 100 meters inan area with clear line of sight. Bluetooth is an open wireless protocolfor exchanging data over short distances from fixed and mobile devices,creating personal area networks (PANs). The cellular phone may receivethe voice over internet protocol (VoIP) data via the WiFi module andfurther transmit the VoIP data through an established PAN to theBluetooth handset, and vice versa. Alternatively, the cellular phone maytransmit digital music through the established PAN to be played back inthe Bluetooth handset. The WLAN and Bluetooth systems both occupy asection of the 2.4 GHz Industrial, Scientific, and Medical (ISM) band,which is 83 MHz-wide. Due to cost issues as well as space requirementsfor components, modern electronic devices, such as cellular phones,Ultra-Mobile PCs (UMPCs) or others, are equipped with WiFi and Bluetoothmodules sharing a single antenna instead of multiple antennas.

As an example shown in FIG. 2, a Bluetooth system uses a FrequencyHopping Spread Spectrum (FHSS) and hops between 79 different 1 MHz-widechannels in a Bluetooth spectrum. A WLAN system uses a Direct SequenceSpread Spectrum (DSSS) instead of a FHSS. A WLAN system carrier remainscentered on one channel, which is 22 MHz-wide. When the WiFi module andthe Bluetooth module are operating simultaneously in the same area, asshown in FIG. 1, the single WLAN channel, which is 22 MHz-wide, occupiesthe same frequency space as 22 out of 79 Bluetooth channels which are 1MHz-wide. When a Bluetooth transmission occurs on a frequency band thatfalls within the frequency space occupied by an ongoing WLANtransmission, a certain level of interference may occur, depending onthe signal strength thereof. Due to the fact that the WiFi module andBluetooth module share the same spectrum and also share a singleantenna, avoiding interference therebetween is required.

FIG. 3 is a diagram illustrating an operation conflict which may occurbetween a WLAN and a Bluetooth communication services sharing a singleantenna. In FIG. 3, the shared single antenna is switched between WLANand Bluetooth communication services in a given time slot fortransceiving data. If the Bluetooth communication service carries audiodata that requires real-time transmission, for example, the SynchronousConnection-Oriented (SCO) packets, the Bluetooth communication servicewould have a higher priority over the WLAN communication service. Inthis case, when a WLAN transceiving process takes place at the same timeas the real-time Bluetooth transceiving process, the time slot will beassigned to the Bluetooth transceiving process and the WLAN transceivingprocess will be blocked. As shown in FIG. 3, the WLAN receivingoperation (Rx operation) 1 occurs in the time slot, while the Bluetoothcommunication service is idle. Therefore, the Rx operation 1 isperformed without interference and an acknowledgement (ACK) message 2 issent to the WLAN AP (such as the AP in FIG. 1) as a reply messageindicating that the Rx operation 1 is finished. Following the Rxoperation 1, another WLAN Rx operation 3 is performed. The Rx operation3 is also performed without interference because the Bluetoothcommunication service is in the idle state. However, an ACK message 4 inresponse to the Rx operation 3 can not be replied to the WLAN AP, as itstime slot is already assigned to the Bluetooth transmitting operation(Tx operation). Accordingly, the Rx operation 3 would be determined tohave failed. In response to the failure, the WLAN AP would re-sent thedata with a lower data rate in an attempt to successfully transmit datato the WLAN module of the mobile device. Unfavorably, the re-performedRx operation 3 (denoted as 5), with a prolonged operation period, willbe more likely to overlap with the Bluetooth transceiving process.Another data re-sent with a lower data rate than that of the priorre-sent would be further attempted, causing more overlap with theBluetooth transceiving process than the prior attempt. As a result, WLANthroughput is highly damaged as the WLAN and Bluetooth wirelesscommunication services sharing a single antenna.

BRIEF SUMMARY OF THE INVENTION

In light of the previously described problems, there exists a need for amethod and system, in which interference may be reduced between aplurality of wireless communication modules sharing a single antenna forsimultaneous operations.

One aspect of the invention discloses a wireless communications system,comprising a first wireless communications module and a second wirelesscommunications module. The first wireless communications module isconfigured to transmit or receive a first wireless signal in a firstfrequency band selected from a first frequency range. The secondwireless communications module is configured to transmit or receive asecond wireless signal in a second frequency band selected from a secondfrequency range, and adjust a transmission power of the second wirelesssignal in response to that a frequency offset between the firstfrequency band and the second frequency band falls within apredetermined range.

Another aspect of the invention discloses a method for reducinginterference between a plurality of wireless communications modules in awireless communications device, comprising: transmitting or receiving afirst wireless signal in a first frequency band selected from a firstfrequency range by a first wireless communications module, andtransmitting or receiving a second wireless signal in a second frequencyband selected from a second frequency range by a second wirelesscommunications module; determining whether a frequency offset betweenthe first frequency band and the second frequency band is within apredetermined range; and adjusting a transmission power of the secondwireless signal in response to that the frequency offset between thefirst frequency band and the second frequency band is within thepredetermined range.

Another aspect of the invention discloses another wirelesscommunications system, comprising a first wireless communications moduleand a second wireless communications module. The first wirelesscommunications module is configured to transmit or receive a pluralityof first wireless signals. The second wireless communications module isconfigured to transmit or receive a plurality of second wirelesssignals, and adjust a transmission power of the second wireless signalsin response to that a signal indicator of the first or second wirelesssignals meets a predetermined criterion.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 shows a cellular phone connecting to a Wireless Local AreaNetwork (WLAN) via a WLAN module thereof as well as communicating with aBluetooth handset through a Bluetooth module thereof;

FIG. 2 shows a diagram of Bluetooth frequency Hopping;

FIG. 3 shows a diagram illustrating an operation conflict between a WLANand a Bluetooth wireless communication services sharing a singleantenna;

FIG. 4 shows a diagram illustrating a system for the coexistence betweentwo wireless communications modules sharing a single antenna inaccordance with an embodiment of the invention;

FIG. 5A shows a diagram illustrating a switching device implemented by asingle-pole double-thrown (SPDT) switch in accordance with an embodimentof the invention;

FIG. 5B shows a diagram illustrating a switching device implemented by adouble-pole double-thrown (DPDT) switch in accordance with an embodimentof the invention;

FIG. 6A shows a connection device implemented using an attenuator inaccordance with an embodiment of the invention;

FIG. 6B shows a connection device implemented using a directionalcoupler in accordance with an embodiment of the invention;

FIGS. 7A and 7B show the configurations of a connection device inaccordance with an embodiment of the invention;

FIGS. 8A to 8C show a flowchart of the method for reducing interferencebetween WiFi and the BT modules in accordance with an embodiment of theinvention;

FIGS. 9A and 9B show exemplary power control of the WiFi and BT Txsignals to reduce in-band interference to the BT and WiFi Rx signals,respectively, in accordance with an embodiment of the invention;

FIGS. 10A and 10B show exemplary power control of the WiFi and BT Txsignals to reduce in-band interference to the BT and WiFi Rx signals,respectively, in accordance with another embodiment of the invention;

FIGS. 11A to 11C show a flowchart of the method for reducinginterference between WiFi and the BT modules in accordance with anotherembodiment of the invention;

FIGS. 12A to 12G show a flowchart for handling the coexistence betweenWiFi and BT modules in accordance with an embodiment of the invention,based on the system of FIG. 4;

FIG. 13 shows a diagram illustrating a system for the coexistencebetween two wireless communications modules sharing a single antennaaccording to another embodiment of the invention;

FIGS. 14A to 14G show a flowchart for handling coexistence between WiFiand BT modules according to an embodiment of the invention, based on thesystem of FIG. 13; and

FIG. 15 shows a system for coexistence between a Global PositioningSystem (GPS) and a subsystem sharing a single antenna according to anembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best-contemplated mode of carryingout the invention. This description is made for the purpose ofillustrating the general principles of the invention and should not betaken in a limiting sense. The scope of the invention is best determinedby reference to the appended claims.

FIG. 4 shows a diagram illustrating a system for the coexistence betweentwo wireless communications modules sharing a single antenna inaccordance with an embodiment of the invention. The system 400 comprisesan antenna 10, a switching device 20, a connection device 30 and awireless communications chipset 100. The wireless communications chipset100 comprises a control unit 110, a WiFi module 120, a BT module 130, aseparator 140, a WiFi Tx front-end 151, a WiFi/BT Rx front-end 152, BTTx front-ends 153 and 155, a BT Rx front-end 154, a balun unit 161, andbalun-switch units 162 and 163. Each of the balun unit 161 and thebalun-switch units 162 and 163 comprises a balun that is used to convertelectrical signals that are balanced with respect to ground(differential) into signals that are unbalanced (single-ended) and viceversa. The balun unit 161 is connected as an input/output (I/O) port(port 1) of the wireless communications chipset 100. The balun-switchunits 162 and 163 serve as another I/O ports (ports 2 and 3) of thewireless communications chipset 100. The switching device 20 and theconnection device 30 may be integrated as a path selection circuit anddisposed on a printed circuit board (PCB).

The WiFi module 120 is connected with the BT module 130 forcommunicating operation statuses and power control information to eachother, so that the transmission power of either the WiFi module 120 orthe BT module 130 may be adjusted to reduce the signal interference tothe other of the WiFi module 120 and the BT module 130. The WiFi Txfront-end 151 is connected to the WiFi module 120 and performs thefront-end functions for transmission, such as modulation of thetransmitting carrier signals. The WiFi/BT Rx front-end 152 is connectedto the separator 140 and performs the front-end functions for reception,such as demodulation of the received carrier signals. The separator 140is configured to separate the WiFi and BT Rx signals in the combinedsignals from the WiFi/BT Rx front-end 152, and to direct the separatedWiFi and BT Rx signals to the WiFi module 120 and the BT module 130,respectively. Similarly, both of the BT Tx front-ends 153 and 155 areconnected to the BT module 130 and perform the front-end functions fortransmission, and the BT Rx front-end 154 is connected to the BT module130 and performs the front-end functions for reception. The operationstates of the WiFi Tx front-end 151, the WiFi/BT Rx front-end 152, theBT Tx front-end 153, the BT Rx front-end 154, and the BT Tx front-end155 are controlled by the control unit 110. By setting the operationstate to “ON”, the corresponding front-end unit will be activated. Onthe contrary, by setting the operation state to “OFF”, the correspondingfront-end unit will be deactivated. Or, alternatively, the operationstate may be set to “DOWN” so that the corresponding front-end unitoperates in an idle mode in which most of circuits are shut down and alow-rate clock is working to reduce power consumption. It is to beunderstood that, when any front-end unit is set to “OFF” or “DOWN”, thecorresponding transmission or reception capability is loss. The controlunit 110 may also operate as a packet traffic arbitrator (PTA) toreceive the traffic requests from both of the WiFi module 120 and the BTmodule 130, and to determine whether the WiFi traffic request hascollided with the BT traffic request in a time period. If a collisionhas occurred, the control unit 110 may grant both of the trafficrequests or may only grant one of the traffic requests while rejectingthe other, depending on the frequency bands, priorities, operation types(e.g. Tx/Rx operation), power levels or others parameters of the trafficrequests. Additionally, the control unit 110 further controls the switchdevice 20 to connect the terminal 22 to the terminal 24 or 26, thebalun-switch unit 162 to connect the terminal 162-2 to the terminal162-4 or 162-6, and the balun-switch unit 163 to connect the terminal163-2 to the terminal 163-4 or 163-6. Accordingly, by controlling theswitch device 20, the balun-switch unit 162, and the balun-switch unit163, and controlling the operation states of the WiFi Tx front-end 151,the WiFi/BT Rx front-end 152, the BT Tx front-end 153, the BT Rxfront-end 154, and the BT Tx front-end 155, the control unit 110determines the antenna path of the WiFi module 120 and the BT module130. It is to be understood that the control unit 110 may be integratedinto the WiFi module 120 or the BT module 130 to reduce hardware costs.

The switching device 20 may be implemented by a single-poledouble-thrown (SPDT) switch, which consists of three terminals 22, 24and 26 and is configured to selectively connect the terminal 22 to theterminal 24 and 26, as shown in FIG. 5A. In addition, the terminals 24and 26 are connected to the ports 1 and 2 of the wireless communicationschipset 100, respectively. In other embodiments, the switching device 20may also be implemented by a double-pole double-thrown (DPDT) as shownin FIG. 5B. The terminal 24 is selectively connected to the terminals 22or 28, and the terminal 26 is selectively connected to the terminals 22or 28. The terminal 28 may be coupled or connected to an external nodefor impedance matching.

The connection device 30 consists of three ports 32, 34 and 36 and isconfigured to couple the ports 32 and 34 to form a transceiving path(through path), and to couple the ports 32 and 36 to form anothertransceiving path (coupled path), wherein the port 34 is isolated fromthe port 36 by substantially 20 dB and the electrical signals passingthrough the path between ports 32 and 36 are substantially attenuated by6 or 10 dB. Referring to FIG. 6A, the connection device 30 may containan attenuator attenuating electrical signals passing through the ports32 and 36 by 20 dB. Alternatively, the connection device 30 may containa directional coupler, as shown in FIG. 6B, in which the ports 32 and 34are coupled as a through path, the port 36 and an external node 38 areconnected as a through path, the ports 32 and 36 are coupled as acoupled path, and the ports 34 and 36 are isolated with a loss around20-40 dB. The through path is direct or indirect through and theexternal node 38 may be a resistor (for example, a 50Ω resistor or a 50Ωequivalent termination). It is noted that the through path between theports 32 and 34 may have a loss of 0.5 dB substantially while thecoupled path between ports 32 and 36 may have a loss of 10 dBsubstantially, or the through path between ports 32 and 34 may have aloss of 1.2 dB substantially while the coupled path between ports 32 and36 may have a loss of 6 dB substantially.

FIG. 7A and FIG. 7B illustrate two embodiments of the directionalcoupler shown in FIG. 6B. Referring to FIG. 7A, two transmission linesare set sufficiently close together, such that electrical signals (orenergy) directed from the port 32 (connected to a port called an inputport) to the port 34 (connected to a port called a transmitted port) iscoupled to the port 36 (connected to a port called a coupled port).Similarly, referring to FIG. 7B, electrical signals (or energy) directedfrom the ports 36 (connected to a port called an input port) to atransmitted port (such as port 38 in FIG. 6B) is coupled to the port 32(connected to a port called a coupled port) and isolated from the port34 (connected to a port called an isolated port), such that the coupledsignals can be added to electrical signals passing between the ports 32and 34.

In addition to the attenuator (FIG. 6A) and the directional coupler(FIG. 6B), the connection device 30 may be implemented in a powerdivider, in which the ports 34 and 36 are isolated and both have a lossof 3 dB ideally (3.5 dB in practice). Furthermore, the connection device30 may be implemented in a power splitter. The structure of the powersplitter is similar to the power divider, but with different lossesbetween the output ports. For a power splitter, the losses of the ports34 and 36 are different. For example, the port 36 may have a loss of 10dB while the port 34 may have a loss of 0.5 dB, or the port 36 may havea loss of 6 dB while the port 34 may have a loss of 1 dB. In addition,the connection device 30 may be implemented by a PCB pad with an inputport and two output ports, in which one of the output ports has a lossof NdB and another output port has a loss of smaller than 1 dB, asdesigned based on requirement. It is noted that the power splitter maybe implemented using a directional coupler, such as the one shown inFIG. 6B, with the port 38 connected to a resistor for impedance matchingand ports 34 and 36 being isolated. With the power splitter implementedusing a directional coupler as shown in FIG. 6B, the port 36 may have aloss of 10 dB while the port 34 may have a loss of 0.5 dB, or the port36 may have a loss of 6 dB while the port 34 may have a loss of 1 dB.

FIGS. 8A to 8C show a flowchart of the method for reducing interferencebetween the WiFi module 120 and the BT module 130 in accordance with anembodiment of the invention. Although the flow is explained withreference to the system 400 as shown in FIG. 4, the present invention isnot limited thereto. Other antenna structures or tranceiverconfigurations capable of conducting co-existence of two or morecommunications modules can be applied as well. To begin, the WiFi module120 determines the frequency band for transmitting and receiving WiFisignals when connected to an AP (step S801). The WiFi module 120 maydetermine the frequency band when connected to the AP with reference toa channel table. In some conditions, such as WiFi module 120 isconfigured to comply with 802.11n specification, the WiFi module 120determines the frequency band with a primary channel and a secondarychannel. When the frequency band is determined, the WiFi module 120calculates the in-band ranges for the BT Rx signals and the WiFi Rxsignals (step S802), wherein the in-band ranges for the BT Rx signalsand the WiFi Rx signals indicate the frequency ranges where the BT Rxsignals and the WiFi Rx signals may have in-band interference caused bythe WiFi Tx signals and the BT Tx signals, respectively, as will befurther illustrated in FIGS. 9A and 9B. In one embodiment, the in-bandinterference may be caused when both of the WiFi signals and the BTsignals are transmitted or received in the same frequency; while inother embodiments, the in-band interference may be caused when the WiFisignals and the BT signals are transmitted or received in nearbyfrequencies. By calculating the in-band ranges for the BT Rx signals andthe WiFi Rx signals, the WiFi module 120 may generate two channelbitmaps which indicate the in-band ranges for the BT Rx signals, whereinone channel bitmap indicates which channels carrying BT Rx signals mayhave in-band interference caused by the WiFi Tx signals in the primarychannel, and the other channel bitmap indicates which channels carryingBT Rx signals may have in-band interference caused by the WiFi Txsignals in the secondary channel. Likewise, the WiFi module 120 maygenerate two channel bitmaps which indicate the in-band ranges for theWiFi Rx signals, wherein one channel bitmap indicates which channelscarrying BT Tx signals may cause in-band interference to the WiFi Rxsignals in the primary channel, and the other channel bitmap indicateswhich channels carrying BT Tx signals may cause in-band interference tothe WiFi Rx signals in the secondary channel. Subsequently, the WiFimodule 120 sends the in-band ranges for the WiFi Rx signals and the BTRx signals to the BT module 130 (step S803). When the in-band ranges forthe WiFi Rx signals and the BT Rx signals from the WiFi module 120 arereceived, it is determined whether an Rx operation or a Tx operation isgoing to be performed by the BT module 130 in a forthcoming time period(step S804). If the BT module 130 occupies the time period for an Rxoperation, the BT module 130 determines whether in-band interference maybe caused to the BT Rx signals by potential WiFi Tx signals in the timeperiod according to the in-band range for the BT Rx signals and thetraffic pattern of the BT Rx signals (step S805). In one embodiment, theBT module 130 may determine whether there may be in-band interference bychecking if any one of the next N hopped channels used by the BT Rxsignals is in the in-band range for the BT Rx signals. That is, if oneof the next N hopped channels used by the BT Rx signals is in thefrequency band or near the frequency band of the WiFi Tx signals, thenin-band interference may be caused to the BT Rx signals by potentialWiFi Tx signals. After determining whether in-band interference may becaused, the BT module 130 sends to the WiFi module 120, thedetermination result, and the signal indicators of the BT Rx signals(step S806). In one embodiment, the BT module 130 may also send thetraffic pattern information of the BT Rx signals to the WiFi module 120,including the starting time, duration, and repeating interval of the BTRx signals. When the determination result is received, it is determinedwhether a Tx operation is going to be performed by the WiFi module 120in the time period (step S807). If so, the WiFi module 120 adjusts thetransmission power of the WiFi Tx signals according to the determinationresult and the signal indicators of the BT Rx signals and the WiFi Txsignals. To be more specific, it is first determined whether thedetermination result indicates that in-band interference may be caused(step S808). If the determination result indicates to the WiFi module120 that the WiFi Tx signals may cause in-band interference to the BT Rxsignals, the WiFi module 120 decreases the transmission power of theWiFi Tx signals according to the signal indicators of the BT Rx signalsand the WiFi Tx signals, so that the BT Rx signals may be successfullyreceived (step S809). Additionally, the WiFi module 120 may furtherdetermine when to decreases the transmission power of the WiFi Txsignals according to the traffic pattern information of the BT Rxsignals. Otherwise, if the determination result indicates to the WiFimodule 120 that the WiFi Tx signals do not cause in-band interference tothe BT Rx signals, the WiFi module 120 may use normal power to transmitthe WiFi Tx signals (step S810). Subsequent to step S807, if not, theprocess goes back to wait for the next upcoming traffic requests fromthe WiFi module 120 and the BT module 130. The signal indicators of theBT Rx signals and the WiFi Tx signals may include received signalstrength indication (RSSI), signal to noise ratio (SNR), adjacentchannel interference (ACI), packet error rate (PER), or bit error rate(BER) of the BT Rx signals and the WiFi Tx signals, respectively. Inother embodiments, the transmission power of the WiFi Tx signals mayalso be adjusted according to the frequency offset between thefrequencies or channels used by the BT Rx signals and the WiFi Txsignals, or the transceiving modulation types of the BT Rx signals andthe WiFi Tx signals.

FIG. 9A is a diagram illustrating exemplary power control of the WiFi Txsignals to reduce in-band interference to the BT Rx signals inaccordance with an embodiment of the invention. As shown in FIG. 9A, theWiFi Tx signals are transmitted within the frequency range f1, and theBT Rx signals are received in a hopping frequency sequence. Theadjustment of the transmission power for the WiFi Tx signals isdetermined according to the frequency offset between the WiFi Tx signalsand the BT Rx signals. The in-band range for BT Rx signals (depicted asf1′) indicates a frequency range in which in-band interference may beoccurred to the BT Rx signals received with the hopped frequency beingin the frequency range. The in-band range f1′ may be determinedaccording to the operational frequency ranges and the anti-interferenceability of the WiFi module 120 and the BT module 130. As shown in FIG.9A, when the hopped frequency of the BT Rx signals is not within thein-band range f1′ (depicted with solid arrows as shown in FIG. 9A) orthe frequency offset between the hopped frequency of the BT Rx signalsand the frequency range f1 of the WiFi Tx signals is greater than d1,the WiFi module 120 may use normal transmission power P1 to transmit theWiFi Tx signals without causing in-band interference to the BT Rxsignals. When the hopped frequency of the BT Rx signals is within thein-band range f1′ (depicted with dashed arrows as shown in FIG. 9A) orthe frequency offset between the hopped frequency of the BT Rx signalsand the frequency range f1 of the WiFi Tx signals is less than or equalto d1, the WiFi module 120 may decrease the transmission power from P1to P2 to reduce the in-band interference to the BT Rx signals. Inaddition, though not shown, the WiFi module 120 may further decrease thetransmission power to further reduce the in-band interference to the BTRx signals when the hopped frequency of the BT Rx signals is in f1. Inaddition to the frequency offset, the adjustment of the transmissionpower for the WiFi Tx signals may be determined according to thetransmitting or receiving modulation type(s) of the WiFi Tx signalsand/or the BT Rx signals. It is noted that the transmission power of theWiFi Tx signal is decreased in a way that the in-band interference tothe BT Rx signals is reduced to satisfy a minimum requirement for the BTRx signals to be successfully received by the BT module 130. Forexample, as shown in FIG. 10A, the region R1 represents the situationwhere both of the signal qualities of the WiFi and BT signals are good,i.e. both of the RSSIs of the WiFi and BT signals are greater than athreshold value, and the region R2 represents the situation where bothof the signal qualities of the WiFi and BT signals are bad, i.e. both ofthe RSSIs of the WiFi and BT signals are less than the threshold value.In the region R1, the line L1 represents the WiFi Tx power correspondingto the RSSIs of the WiFi and BT signals, where the WiFi Tx power may beincreased as the RSSI of the BT Rx signals increases and decreased asthe RSSI of the BT signals decreases. The slope of the line L1 may bedetermined according to anti-interference ability of the WiFi module 120and the BT module 130. In the region R2, since both of the signalqualities of the WiFi and BT signals are bad, adjusting the power of theWiFi Tx signals may not help to maintain the successful reception of theBT Rx signals, so arbitration between the traffics of the WiFi module120 and the BT module 130 may be employed. Since arbitration is employedto make sure only one module is active for the time period, the WiFimodule 120 may use the original transmission power for the WiFi Txsignals, as depicted with the line L1′. In another embodiment, thetransmission power for the WiFi Tx signals may be adjusted in ahierarchical fashion. For the RSSIs of the WiFi and BT signals in afirst predetermined range, the transmission power for the WiFi Txsignals may be adjusted to a first level, and for the RSSIs of the WiFiand BT signals in a second predetermined range, the transmission powerfor the WiFi Tx signals may be adjusted to a second level, and so on.Although the embodiments described above use the RSSIs as signalindicators for the WiFi and BT signals, other signal indicators, such assignal to noise ratios (SNR), adjacent channel interferences (ACI),packet error rates (PER), and bit error rates (BER), may be employed fordetermining the adjustment of the transmission power of the WiFi module120.

Subsequent to step S804, if the BT module 130 occupies the time periodfor a Tx operation, the BT module 130 prepares and sends the trafficparameters of the BT Tx signals to the WiFi module 120 (step S811). Thetraffic parameters of the BT Tx signals may include informationconcerning when the BT Tx signals will be transmitted, and what powerlevel, modulation type, and channel will be used for transmitting the BTTx signals. When the traffic parameters of the BT Tx signals arereceived from the BT module 130, it is determined whether an Rxoperation is going to be performed by the WiFi module 120 in the timeperiod (step S812). If so, the BT module 130 determines whether the BTTx signals may cause in-band interference to the WiFi Rx signals in thetime period according to the in-band range for the WiFi Rx signals andthe traffic parameters of the WiFi Rx signals (step S813). If so, the BTmodule 130 decreases the transmission power of the BT Tx signalsaccording to the signal indicators of the WiFi Rx signals and the BT Txsignals, so that the WiFi Rx signals may be successfully received (stepS814). Otherwise, if the BT Tx signals do not cause in-band ranges tothe WiFi Rx signals in the time period, then normal transmission powerof the BT Tx signals may be used (step S815). Subsequent to step S812,if not, the process goes back to wait for the next upcoming trafficrequests from the WiFi module 120 and the BT module 130. The signalindicators of the BT Tx signals and the WiFi Rx signals may includereceived signal strength indication (RSSI), signal to noise ratio (SNR),adjacent channel interference (ACI), packet error rate (PER), or biterror rate (BER) of the BT Tx signals and the WiFi Rx signals,respectively. In other embodiments, the transmission power of the BT Txsignals may also be adjusted according to the frequency offset betweenthe frequencies or channels used by the WiFi Rx signals and the BT Txsignals, or the transceiving modulation types of the WiFi Rx signals andthe BT Tx signals.

FIG. 9B is a diagram illustrating exemplary power control of the BT Txsignals to reduce in-band interference to the WiFi Rx signals inaccordance with an embodiment of the invention. As shown in FIG. 9B, theWiFi Rx signals are received in the frequency range f2, and the BT Txsignals are transmitted in a hopping frequency sequence. The in-bandrange for the WiFi Rx signals (depicted as f2′) indicates a frequencyrange in which in-band interference may be occurred to the WiFi Rxsignals when the BT Tx signals are transmitted with the hopped frequencybeing in the frequency range. The in-band range f2′ may be determinedaccording to the operational frequency ranges and the anti-interferenceability of the WiFi module 120 and the BT module 130. As shown in FIG.9B, when the hopped frequency of the BT Tx signals is not within thein-band range f2′ (depicted with solid arrows as shown in FIG. 9B) orthe frequency offset between the hopped frequency of the BT Tx signalsand the frequency range f2 of the WiFi Rx signals is greater than d2,the BT module 130 may use normal transmission power P3 to transmit theBT Tx signals without causing in-band interference to the WiFi Rxsignals. When the hopped frequency of the BT Tx signals is within thein-band range f2′ (depicted with dashed arrows as shown in FIG. 9B) orthe frequency offset between the hopped frequency of the BT Tx signalsand the frequency range f2 of the WiFi Rx signals is less than or equalto d2, the BT module 130 may decrease the transmission power from P3 toP4 to reduce the in-band interference to the WiFi Rx signals. Inaddition, though not shown, the BT module 130 may further decrease thetransmission power to further reduce the in-band interference to theWiFi Rx signals when the hopped frequency of the BT Tx signals is in f2.In addition to the frequency offset, the adjustment of the transmissionpower for the BT Tx signals may be determined according to thetransmitting or receiving modulation type(s) of the BT Tx signals and/orthe WiFi Rx signals. It is noted that the transmission power of the BTTx signal is decreased in a way that the in-band interference to theWiFi Rx signals is reduced to satisfy a minimum requirement for the WiFiRx signals to be successfully received by the WiFi module 120. Forexample, as shown in FIG. 10B, the region R1 represents the situationwhere both of the signal qualities of the WiFi and BT signals are good,i.e. both of the RSSIs of the WiFi and BT signals are greater than athreshold value, and the region R2 represents the situation where bothof the signal qualities of the WiFi and BT signals are bad, i.e. both ofthe RSSIs of the WiFi and BT signals are less than the threshold value.In the region R1, the line L2 represents the BT Tx power correspondingto the RSSIs of the WiFi and BT signals, where the BT Tx power may bedecreased as the RSSI of the BT signals increases (i.e. high RSSI of theBT signals indicates that the distance to the peer communication deviceis short, so smaller transmission power may be used) and increased asthe RSSI of the Rx signals decreases (i.e. low RSSI of the BT signalsindicates that the distance to the peer communication device is long, sogreater transmission power may be used). The slope of the line L2 may bedetermined according to the anti-interference ability of the WiFi module120 and the BT module 130. In the region R2, since both of the signalqualities of the WiFi and BT signals are bad, adjusting the power of theBT Tx signals may not help to maintain a successful reception of theWiFi Rx signals, so arbitration between the traffics of the WiFi module120 and the BT module 130 may be employed. Since arbitration is employedto make sure only one module is active for the time period, the BTmodule 130 may use the original transmission power for the BT Txsignals, as depicted with the line L2′. In another embodiment, thetransmission power for the BT Tx signals may be adjusted in ahierarchical fashion. For the RSSIs of the WiFi and BT signals in afirst predetermined range, the transmission power for the BT Tx signalsmay be adjusted to a first level, and for the RSSIs of the WiFi and BTsignals in a second predetermined range, the transmission power for theBT Tx signals may be adjusted to a second level, and so on. Although theembodiments described above use the RSSIs as signal indicators for theWiFi and BT signals, other signal indicators, such as SNR, ACI, PER, andBER, may be employed for determining the adjustment of the transmissionpower of the BT module 130.

FIGS. 11A to 11C show a flowchart of the method for reducinginterference between the WiFi module 120 and the BT module 130 inaccordance with another embodiment of the invention. Similar to thesteps S801 to S803 in FIG. 8, the method in this embodiment also beginswith obtaining the in-band ranges for the BT Rx signals and the WiFi Rxsignals by the WiFi module 120 and the BT module 130 (stepsS1101˜S1103). The method in this embodiment subsequently determineswhether to apply power control according to the traffic parameters andthe signal indicators of both the WiFi module 120 and BT module 130(step S1104). If so, the process proceeds to step S1105. Otherwise, theprocess ends. In one embodiment, power control is applied when both ofthe RSSIs of the BT Rx signals and WiFi Rx signals are greater than agood-quality threshold value. That is, having the RSSIs greater than thegood-quality threshold value means that the signal strength of the BT Rxsignals and WiFi Rx signals is good enough to withstand some level ofinterference without jeopardizing the successful reception of the BT Rxsignals and WiFi Rx signals. In another embodiment, power control maynot be applied when the RSSI of the BT Rx signals or the WiFi Rx signalsis lower than a fair-quality threshold value and the BT Rx signals orthe WiFi Rx signals are for real-time applications. That is, having theRSSI of the BT Rx signals or the WiFi Rx signals lower than thefair-quality threshold value means that the signal strength of the BT Rxsignals or the WiFi Rx signals is too weak to withstand any interferenceand even decreasing the transmission power of the transmitting modulemay still lead to an unsuccessful reception of the BT Rx signals or theWiFi Rx signals. Meanwhile, if the BT Rx signals or the WiFi Rx signalsare for real-time applications, the data carried in the BT Rx signals orthe WiFi Rx signals should be considered critical and the successfulreception of the BT Rx signals or the WiFi Rx signals should be a firstpriority. Subsequent to S1104, if power control is to be applied, aseries of inspections with respect to the operation statuses, thetraffic parameters, and the signal indicators of the WiFi module 120 andBT module 130 are performed to determine whether in-band interferencewill be caused between the WiFi module 120 and BT module 130.Specifically, it is determined whether an Rx operation or a Tx operationis going to be performed by the BT module 130 in a forthcoming timeperiod (step S1105). If the BT module 130 occupies the time period foran Rx operation, the BT module 130 determines whether in-bandinterference may be caused to the BT Rx signals by potential WiFi Txsignals in the time period according to the in-band range for the BT Rxsignals and the traffic pattern of the BT Rx signals (step S1106). Inone embodiment, the BT module 130 may determine whether there may bein-band interference by checking if any one of the next N hoppedchannels used by the BT Rx signals is in the in-band range for the BT Rxsignals. That is, if one of the next N hopped channels used by the BT Rxsignals is in the frequency band or near the frequency band of the WiFiTx signals, then in-band interference may be caused to the BT Rx signalsby potential WiFi Tx signals. After determining whether in-bandinterference may be caused, the BT module 130 sends the determinationresult and the signal indicators of the BT Rx signals to the WiFi module120 (step S1107). In one embodiment, the BT module 130 may also send thetraffic pattern information of the BT Rx signals to the WiFi module 120,including the starting time, duration, and repeating interval of the BTRx signals. When the determination result is received, it is determinedwhether a Tx operation is going to be performed by the WiFi module 120in the time period (step S1108). If so, the WiFi module 120 adjusts thetransmission power of the WiFi Tx signals according to the determinationresult and the signal indicators of the BT Rx signals and the WiFi Txsignals. To be more specific, it is first determined whether thedetermination result indicates that in-band interference may be caused(step S1109). If the determination result indicates to the WiFi module120 that the WiFi Tx signals may cause in-band interference to the BT Rxsignals, the WiFi module 120 decreases the transmission power of theWiFi Tx signals according to the signal indicators of the BT Rx signalsand the WiFi Tx signals, so that the BT Rx signals may be successfullyreceived (step S1110). It is noted that the transmission power of theWiFi Tx signal is decreased in a way that the in-band interference tothe BT Rx signals is reduced to satisfy the minimum requirement for theBT Rx signals to be successfully received by the BT module 130.Otherwise, if the determination result indicates to the WiFi module 120that the WiFi Tx signals do not cause in-band interference to the BT Rxsignals, the WiFi module 120 may use normal power to transmit the WiFiTx signals (step S1111). Subsequent to step S1108, if not, the processgoes back to wait for the next upcoming traffic requests from the WiFimodule 120 and the BT module 130. The signal indicators of the BT Rxsignals and the WiFi Tx signals may include RSSI, SNR, ACI, PER, or BERof the BT Rx signals and the WiFi Tx signals, respectively. In otherembodiments, the transmission power of the WiFi Tx signals may also beadjusted according to the frequency offset between the frequencies orchannels used by the BT Rx signals and the WiFi Tx signals, or thetransceiving modulation types of the BT Rx signals and the WiFi Txsignals.

Subsequent to step S1105, if the BT module 130 occupies the time periodfor a Tx operation, the BT module 130 prepares and sends the trafficparameters of the BT Tx signals to the WiFi module 120 (step S1112). Thetraffic parameters of the BT Tx signals may include informationconcerning when the BT Tx signals will be transmitted, and what powerlevel, modulation type, and channel will be used for transmitting the BTTx signals. When the traffic parameters of the BT Tx signals arereceived from the BT module 130, it is determined whether an Rxoperation is going to be performed by the WiFi module 120 in the timeperiod (step S1113). If so, the BT module 130 determines whether the BTTx signals may cause in-band interference to the WiFi Rx signals in thetime period according to the in-band range for the WiFi Rx signals andthe traffic parameters of the WiFi Rx signals (step S1114). If so, theBT module 130 decreases the transmission power of the BT Tx signalsaccording to the signal indicators of the WiFi Rx signals and the BT Txsignals, so that the WiFi Rx signals may be successfully received (stepS1115). Otherwise, if the BT Tx signals do not cause in-band ranges tothe WiFi Rx signals, then normal transmission power of the BT Tx signalsmay be used (step S1116). Subsequent to step S1113, if not, the processgoes back to wait for the next upcoming traffic requests from the WiFimodule 120 and the BT module 130. The signal indicators of the BT Txsignals and the WiFi Rx signals may include RSSI, SNR, ACI, PER, or BERof the BT Tx signals and the WiFi Rx signals, respectively. In otherembodiments, the transmission power of the BT Tx signals may also beadjusted according to the frequency offset between the frequencies orchannels used by the WiFi Rx signals and the BT Tx signals, or thetransceiving modulation types of the WiFi Rx signals and the BT Txsignals. It is noted that the transmission power of the WiFi Tx signalsor the BT Tx signals in step S1109 or S1114 is decreased in a way thatthe in-band interference to the BT Rx signals or the WiFi Rx signals isreduced to satisfy the minimum requirement for the BT Rx signals or theWiFi Rx signals to be successfully received by the BT module 130 or theWiFi module 120, respectively.

For the components and connection configurations therebetween in thewireless communications chipset 100 described above, it is noted thatthe WiFi module 120 has one Tx front-end and one Rx front-end, while theBT modules 130 has two Tx front-ends and two Rx front-ends. After thetransmission power control is performed as described above, theoperation types of the system 400 with respect to the Tx front-ends andRx front-end of the WiFi module 120 and the BT module 130 are determinedTable 1 below depicts a combination of potential operation typesperformed by the system 400 according to an embodiment of the invention:

TABLE 1 Operation Type Mode WiFi_Tx WiFi_Rx BT_Tx BT_Rx Mode 1 0 0 1(Port 2) 0 Mode 2 0 0 0 1 (Port 2) Mode 3 1 (Port 1) 0 0 0 Mode 4 0 1(Port 2) 0 0 Mode 5 0 1 (Port 2) 1 (Port 3) 0 Mode 6 0 1 (Port 2) 0 1(Port 3) Mode 7 1 (Port 1) 0 0 1 (Port 3) Mode 8 1 (Port 1) 0 1 (Port 3)0 Mode 9 0 1 (Port 2) 1 (Port 2) 0 Mode 10 0 1 (Port 2) 0 1 (Port 2)Mode 11 1 (Port 1) 0 0 1 (Port 2) Mode 12 1 (Port 1) 0 1 (Port 2) 0

In Table 1 above, “1” means TRUE, representing activation of acorresponding operation, whereas “0” means FALSE, representingdeactivation of a corresponding operation. The operation modes in Table1 above will be explained in more details with references to theflowchart in FIG. 12 below.

FIGS. 12A to 12G show a flowchart of the coexistence between WiFi and BTmodules handled by the control unit 110 in accordance with an embodimentof the invention. The procedure begins with obtaining informationregarding potential operation(s) that is/are going to be performed bythe WiFi module 120 and BT module 130 in a forthcoming time period (stepS1201). Next, a series of inspections with respect to the obtainedinformation are accordingly performed to determine whether only one orboth of the WiFi module 120 and BT module 130 occupy a time period, andwhether the time period occupied for a Tx/Rx operation by one modulecollides with an Tx/Rx operation by the other module. Specifically, itis determined whether only the BT module 130 occupies the time periodfor a Tx operation (step S1202). If so, the control unit 110 sendscontrol signals to activate the BT Tx front-end 153, switch thebalun-switch unit 162 to the BT Tx front-end 153, and switch theswitching device 20 to the port 2 for the time period (mode 1) (stepS1203), thereby enabling the BT Tx signals to be transmitted from the BTmodule 130 via the BT Tx front-end 153, the port 2, and the through pathbetween the ports 34 and 32 in sequence to the antenna 10. Subsequent tostep S1202, if not, it is determined whether only the BT module 112occupies the time period for an Rx operation (step S1204). If so, thecontrol unit 110 sends control signals to activate the WiFi/BT Rxfront-end 152, switch the balun-switch unit 162 to the WiFi/BT Rxfront-end 152, and switch the switching device 20 to the port 2 for thetime period (mode 2) (step S1205), thereby enabling the BT Rx signals tobe received from the antenna 10 by the BT module 130 via the throughpath between the ports 32 and 34, the port 2, the WiFi/BT Rx front-end152, and the separator 140 in sequence. Subsequent to step S1104, ifnot, it is determined whether only the WiFi module 120 occupies the timeperiod for a Tx operation (step S1206). If so, the control unit 110sends control signals to activate the WiFi Tx front-end 151 and switchthe switching device 20 to the port 1 for the time period (mode 3) (stepS1207), thereby enabling the WiFi Tx signals to be transmitted from theWiFi module 120 via the WiFi Tx front-end 151, the port 1, and thethrough path between the ports 34 and 32 in sequence to the antenna 10.Subsequent to step S1206, if not, it is determined whether only the WiFimodule 120 occupies the time period for an Rx operation (step S1208). Ifso, the control unit 110 sends control signals to activate the WiFi/BTRx front-end 152, switch the balun-switch unit 162 to the WiFi/BT Rxfront-end 152, and switch the switching device 20 to the port 2 for thetime period (mode 4) (step S1209), thereby enabling the WiFi Rx signalsto be received from the antenna 10 by the WiFi module 120 via thethrough path between the ports 32 and 34, the port 2, the WiFi/BT Rxfront-end 152, and the separator 140 in sequence.

Subsequent to step S1208, if not, it means that both of the WiFi module120 and the BT module 130 occupy the time period for their operations.However, it is noted that when a WiFi Rx/Tx operation and a BT Rx/Txoperation both take place at the same time, the WiFi Rx/Tx signals mayinterfere with the BT Rx/Tx signals, and vice versa. Consequently, thelarger the wanted power of the WiFi Tx signals is, the greater theinterferences are to the BT Rx/Tx signals, and vice versa. For thisreason, it is determined whether transceiving statuses for the WiFiRx/Tx signals and the BT Rx/Tx signals are in an operational range wherecoexistence is achievable (step S1210). The transceiving status may bewanted power, RSSI, historical PER, historical BER, SNR, orinterference-to-signal ratio (ISR) of the WiFi Rx/Tx signals or the BTRx/Tx signals. In addition, the transceiving status may be a certainnumber of reconnections for historical WiFi Rx/Tx operations or the BTRx/Tx operations.

Note that for the cases in which the WiFi module 120 and the BT module130 occupy the time period for Tx operation and Rx operation,respectively, or the WiFi module 120 and the BT module 130 occupy thetime period for Rx operation and Tx operation, respectively, if thepower control as described in FIG. 8 has been performed due to potentialin-band interference between the WiFi module 120 and the BT module 130,then the adjusted power may ensure that the transceiving statuses forthe WiFi Rx/Tx signals and the BT Rx/Tx signals are in an operationalrange where coexistence is achievable.

Subsequent to step S1210, if so, it is determined whether the WiFimodule 120 and the BT module 130 occupy the time period for Rx and Txoperations, respectively (step S1211). If so, the control unit 110 sendscontrol signals to activate the WiFi/BT Rx front-end 152 and the BT Txfront-end 155, switch the balun-switch units 162 and 163 to the WiFi/BTRx front-end 152 and the BT Tx front-end 155, respectively, and switchthe switching device 20 to the port 2 for the time period (mode 5) (stepS1212), thereby enabling the WiFi Rx signals to be received from theantenna 10 by the WiFi module 120 via the through path between the ports32 and 34, the port 2, the WiFi/BT Rx front-end 152, and the separator140 in sequence, along with the BT Tx signals to be transmitted from theBT module 130 via the BT Tx front-end 155, the port 3, and the coupledpath between the ports 32 and 36 in sequence to the antenna 10.Subsequent to step S1211, if not, it is determined whether both of theWiFi module 120 and the BT module 130 occupy the time period for Rxoperations (step S1213). If so, the control unit 110 sends controlsignals to activate the WiFi/BT Rx front-end 152 and the BT Rx front-end154, switch the balun-switch units 162 and 163 to the WiFi/BT Rxfront-end 152 and the BT Rx front-end 154, respectively, and switch theswitching device 20 to the port 2 for the time period (mode 6) (stepS1214), thereby enabling the WiFi Rx signals to be received from theantenna 10 by the WiFi module 120 via the through path between the ports32 and 34, the port 2, the WiFi/BT Rx front-end 152, and the separator140 in sequence, along with the BT Rx signals to be received from theantenna 10 by the BT module 130 via the coupled path between the ports32 and 36, the port 3, and the BT Rx front-end 154 in sequence.Subsequent to step S1213, if not, it is determined whether the WiFimodule 120 and the BT module 130 occupy the time period for Tx and Rxoperations, respectively (step S1215). If so, the control unit 110 sendscontrol signals to activate the WiFi Tx front-end 151 and the BT Rxfront-end 154, switch the balun-switch unit 163 to the BT Rx front-end154, and switch the switching device 20 to the port 1 for the timeperiod (mode 7) (step S1216), thereby enabling the WiFi Tx signals to betransmitted from the WiFi module 120 via the WiFi Tx front-end 151, thebalun unit 161, the port 1, and the through path between the ports 32and 34 in sequence to the antenna 10, along with the BT Rx signals to bereceived from the antenna 10 by the BT module 130 via the coupled pathbetween the ports 32 and 36, the port 3, and the BT Rx front-end 154 insequence. Subsequent to step S1215, if not, it is determined whetherboth of the WiFi module 120 and the BT module 130 occupy the time periodfor Tx operations (step S1217). If so, the control unit 110 sendscontrol signals to activate the WiFi Tx front-end 151 and the BT Txfront-end 155, switch the balun-switch unit 163 to the BT Tx front-end155, and switch the switching device 20 to the port 1 for the timeperiod (mode 8) (step S1218), thereby enabling the WiFi Tx signals to betransmitted from the WiFi module 120 via the WiFi Tx front-end 151, thebalun unit 161, the port 1, and the through path between the ports 32and 34 in sequence to the antenna 10, along with the BT Tx signals to betransmitted from the BT module 130 via the BT Tx front-end 155, the port3, and the coupled path between the ports 32 and 36 in sequence to theantenna 10.

Subsequent to step S1210, if not, it is determined whether the WiFimodule 120 and the BT module 130 occupy the time period for Rx and Txoperations, respectively (step S1219). If so, the control unit 110determines whether a collision has occurred in the traffic requests fromthe WiFi module 120 and the BT module 130, and arbitrates which trafficrequest is to be granted when a collision has occurred (step S1220). Ifthe granted traffic request is from the WiFi module 120, the controlunit 110 sends control signals to activate the WiFi/BT Rx front-end 152,switch the balun-switch unit 162 to the WiFi/BT Rx front-end 152, andswitch the switching device 20 to the port 2 for the time period (mode9) (step S1221), thereby enabling the WiFi Rx signals to be receivedfrom the antenna 10 by the WiFi module 120 via the through path betweenthe ports 32 and 34, the port 2, the WiFi/BT Rx front-end 152, and theseparator 140 in sequence. If the granted traffic request is from the BTmodule 130, the control unit 110 sends control signals to activate theBT Tx front-end 153, switch the balun-switch unit 162 to the BT Txfront-end 153, and switch the switching device 20 to the port 2 for thetime period (mode 9) (step S1222), thereby enabling the BT Tx signals tobe transmitted from the BT module 130 via the BT Tx front-end 153, thebalun-switch unit 162, the port 2, and the through path between theports 32 and 34 in sequence to the antenna 10. Subsequent to step S1219,if not, it is determined whether both of the WiFi module 120 and the BTmodule 130 occupy the time period for Rx operations (step S1223). If so,the control unit sends control signals to activate the WiFi/BT Rxfront-end 152, switch the balun-switch unit 162 to the WiFi/BT Rxfront-end 152, and switch the switching device 20 to the port 2 for thetime period (mode 10) (step S1224), thereby enabling a combined signalto be received from the antenna 10 by the separator 140 via the throughpath between ports 32 and 34, the port 2, and the WiFi/BT Rx front-end152 in sequence. Thereafter, the separator 140 separates them into theWiFi and BT Rx signals and further forwarded to the WiFi module 120 andBT module 130, respectively. Subsequent to step S1223, if not, it isdetermined whether the WiFi module 120 and the BT module 130 occupy thetime period for Tx and Rx operations, respectively (step S1225). If so,the control unit 110 determines whether a collision has occurred in thetraffic requests from the WiFi module 120 and the BT module 130, andarbitrates which traffic request is to be granted when a collision hasoccurred (step S1226). If the granted traffic request is from the WiFimodule 120, the control unit 110 sends control signals to activate theWiFi Tx front-end 151 and switch the switching device 20 to the port 1for the time period (mode 11) (step S1227), thereby enabling the WiFi Txsignals to be transmitted from the WiFi module 120 via the WiFi Txfront-end 151, the balun unit 161, the port 1, and the through pathbetween the ports 32 and 34 in sequence to the antenna 10. If thegranted traffic request is from the BT module 130, the control unit 110sends control signals to activate the WiFi/BT Rx front-end 152, switchthe balun-switch unit 162 to the WiFi/BT Rx front-end 152, and switchthe switching device 20 to the port 2 for the time period (mode 11)(step S1228), thereby enabling the BT Rx signals to be received from theantenna 10 by the BT module 130 via the through path between the ports32 and 34, the port 2, the WiFi/BT Rx front-end 152, and the separator140 in sequence. Subsequent to step S1225, if not, it is determinedwhether both of the WiFi module 120 and the BT module 130 occupy thetime period for Tx operations (step S1229). If so, the control unit 110determines whether a collision has occurred in the traffic requests fromthe WiFi module 120 and the BT module 130, and arbitrates which trafficrequest is to be granted when a collision has occurred (step S1230). Ifthe granted traffic request is from the WiFi module 120, the controlunit 110 sends control signals to activate the WiFi Tx front-end 151 andswitch the switching device 20 to the port 1 (mode 12) (step S1231),thereby enabling the WiFi Tx signals to be transmitted from the WiFimodule 120 via the WiFi Tx front-end 151, the balun unit 161, the port1, and the through path between the ports 32 and 34 in sequence to theantenna 10. If the granted traffic request is from the BT module 130,the control unit 110 sends control signals to activate the BT Txfront-end 153, switch the balun-switch unit 162 to the BT Tx front-end153, and switch the switching device 20 to the port 2 for the timeperiod (mode 12) (step S1232), thereby enabling the BT Tx signals to betransmitted from the BT module 130 via the BT Tx front-end 153, the port2, and the through path between the ports 32 and 34 in sequence to theantenna 10.

Those skilled in the art may readily modify the hardware structure ofthe system 400 by implementing the connection device 30 in a 3-portpower splitter having an input port 32 and two output ports 34 and 36.The first path between the input port 32 and the output port 34 has afirst path loss, and the second path between the input port 32 and theoutput port 36 has a second path loss. For a power splitter with equalloss, the path loss of the first and second paths is the same, while itis different for an unequal-loss power splitter. For the coupling valuesfor the power splitter, reference may be made to Table 2 below:

TABLE 2 Coupling Value Power For Through Path Ratio (%)  3 dB 50/50  6dB 75/25  8 dB 85/15 10 dB 90/10 15 dB 97/3  20 dB 99/1 

Taking the coupling value of 3 dB (3 dB directional coupler) forexample, the through path has a path loss of 3 dB substantially, whereasthe coupled path also has a path loss of 3 dB substantially. For the 6dB directional coupler, the through path has a path loss of 1 dBsubstantially, whereas the coupled path also has a path loss of 6 dBsubstantially. For the 10 dB directional coupler, the through path has apath loss of 0.5 dB substantially, whereas the coupled path also has apath loss of 10 dB substantially.

In another embodiment of the invention, an additional switch device maybe included in the system 400, as shown in FIG. 13. Similar to thesystem 400 in FIG. 4, the system 1300 herein also comprises the antenna10 and the wireless communications chipset 100. Regarding descriptionsof the antenna 10 and the elements in the wireless communicationschipset 100 excluding the control unit 110, reference may be made toFIG. 4. However, the elements between the antenna 10 and the wirelesscommunications chipset 100 in the system 1300 are different from thosein the system 400. A switching device 1320, similar to the switchingdevice 20, is configured to selectively connect the terminal 22 to theterminal 24 and 26 as controlled by the control unit 1310, wherein theterminal 24 is connected to the port 1, the terminal 26 is connected tothe port 2, and the terminal 22 is connected to the port 34 of aconnection device 1330. The switching device 1320 may be implemented byan SPDT switch. The connection device 1330 is similar to the connectiondevice 30, in which the ports 32 and 34 are connected via a firstthrough path, the ports 36 and 38 are connected via a second throughpath, the ports 32 and 36 are coupled via a first coupled path, theports 34 and 38 are coupled via a second coupled path, the ports 34 and36 are isolated, and the ports 32 and 38 are isolated, wherein the firstand second through paths are direct or indirect through. In addition,the ports 32 and 38 are connected to the terminals 44 and 46 of aswitching device 1340, respectively, and the port 36 is connected to theport 3. The switching device 1340 is similar to the switching device1320, which consists of three terminals 42, 44, and 46, and isconfigured to selectively connect the terminal 42 to the terminal 44 and46 as controlled by the control unit 1310, wherein the terminal 42 isconnected to the antenna 10. The switching devices 1320 and 1340, andthe connection device 1330 may be integrated as a path selection circuitand disposed on a PCB. Note the first and second through paths may havea loss of 0.5 dB substantially, whereas the first and second coupledpaths may have a loss of 10 dB substantially, or the first and secondthrough paths may have a loss of 1 dB substantially, whereas the firstand second coupled paths may have a loss of 6 dB substantially.

In the following discussion, reference may be made to Table 1 andrelated descriptions. In response to the modification of the pathselection circuit, the control unit 1310 performs similar but differentfunction than that of FIG. 4. FIGS. 14A to 14G show a flowchart of thecoexistence between WiFi and BT modules handled by the control unit 1310in accordance with an embodiment of the invention. The procedure beginswith obtaining information regarding potential operation(s) that is/aregoing to be performed by the WiFi module 120 and BT module 130 in aforthcoming time period (step S1401). Next, a series of inspections withrespect to the obtained information are accordingly performed todetermine whether only one or both of the WiFi module 120 and BT module130 occupy the time period, and whether the time period is occupied fora Tx/Rx operation by one module collides with an Tx/Rx operation by theother module. Specifically, it is determined whether only the BT module130 occupies the time period for a Tx operation (step S1402). If so, thecontrol unit 1310 sends control signals to activate the BT Tx front-end153, switch the balun-switch unit 162 to the BT Tx front-end 153, switchthe switching device 1320 to the port 2, and switch the switching device1340 to the port 32 for the time period (mode 1) (step S1403), therebyenabling the BT Tx signals to be transmitted from the BT module 130 viathe BT Tx front-end 153, the port 2, and the through path between theports 34 and 32 in sequence to the antenna 10. Subsequent to step S1402,if not, it is determined whether only the BT module 130 occupies thetime period for an Rx operation (step S1404). If so, the control unit1310 sends control signals to activate the WiFi/BT Rx front-end 152,switch the balun-switch unit 162 to the WiFi/BT Rx front-end 152, switchthe switching device 1320 to the port 2, and switch the switching device1340 to the port 32 for the time period (mode 2) (step S1405), therebyenabling the BT Rx signals to be received from the antenna 10 by the BTmodule 130 via the through path between the ports 32 and 34, the port 2,the WiFi/BT Rx front-end 152, and the separator 140 in sequence.Subsequent to step S1404, if not, it is determined whether only the WiFimodule 120 occupies the time period for a Tx operation (step S1406). Ifso, the control unit 1310 sends control signals to activate the WiFi Txfront-end 151, switch the switching device 1320 to the port 1, andswitch the switching device 1340 to the port 32 for the time period(mode 3) (step S1407), thereby enabling the WiFi Tx signals to betransmitted from the WiFi module 120 via the WiFi Tx front-end 151, theport 1, and the through path between the ports 34 and 32 in sequence tothe antenna 10. Subsequent to step S1406, if not, it is determinedwhether only the WiFi module 120 occupies the time period for an Rxoperation (step S1408). If so, the control unit 1310 sends controlsignals to activate the WiFi/BT Rx front-end 152, switch thebalun-switch unit 162 to the WiFi/BT Rx front-end 152, switch theswitching device 1320 to the port 2, and switch the switching device1340 to the port 32 for the time period (mode 4) (step S1409), therebyenabling the WiFi Rx signals to be received from the antenna 10 by theWiFi module 120 via the through path between the ports 32 and 34, theport 2, the WiFi/BT Rx front-end 152, and the separator 140 in sequence.

Subsequent to step S1408, if not, it means that both of the WiFi module120 and the BT module 130 occupy the time period for their operations.Since the WiFi Rx/Tx signals may interfere with the BT Rx/Tx signals,and vice versa, it is determined whether the transceiving statuses forthe WiFi Rx/Tx signals and the BT Rx/Tx signals are in an operationalrange where coexistence is achievable (step S1410). The transceiveingstatus may be the wanted power, RSSI, historical PER, historical BER,SNR, or ISR of the WiFi Rx/Tx signals or the BT Rx/Tx signals. Inaddition, the transceiveing status may be a certain number ofreconnections for historical WiFi Rx/Tx operations or the BT Rx/Txoperations. Subsequent to step S1410, if so, it is determined whetherthe WiFi module 120 and the BT module 130 occupy the time period for Rxand Tx operations, respectively (step S1411). If so, the control unit1310 sends control signals to activate the WiFi/BT Rx front-end 152 andthe BT Tx front-end 155, switch the balun-switch units 162 and 163 tothe WiFi/BT Rx front-end 152 and the BT Tx front-end 155, respectively,switch the switching device 1320 to the port 2, and switch the switchingdevice 1340 to the port 32 or 38 for the time period (mode 5) (stepS1412), thereby enabling the WiFi Rx signals to be received from theantenna 10 by the WiFi module via the through path between the ports 32and 34, the port 2, the WiFi/BT Rx front-end 152, and the separator 140in sequence, along with the BT Tx signals to be transmitted from the BTmodule 130 via the BT Tx front-end 155, the port 3, and the through pathbetween the ports 36 and 38 in sequence to the antenna 10. Subsequent tostep S1411, if not, it is determined whether both of the WiFi module 120and the BT module 130 occupy the time period for Rx operations (stepS1413). If so, the control unit 1310 sends control signals to activatethe WiFi/BT Rx front-end 152 and the BT Rx front-end 154, switch thebalun-switch units 162 and 163 to the WiFi/BT Rx front-end 152 and theBT Rx front-end 154, respectively, switch the switching device 1320 tothe port 2, and switch the switching device 1340 to the port 32 or 38for the time period (mode 6) (step S1414), thereby enabling the WiFi Rxsignals to be received from the antenna 10 by the WiFi module 120 viathe through path between the ports 32 and 34, the port 2, the WiFi/BT Rxfront-end 152, and the separator 140 in sequence, along with the BT Rxsignals to be received from the antenna 10 by the BT module 130 via thethrough path between the ports 36 and 38, the port 3, and the BT Rxfront-end 154 in sequence. Subsequent to step S1413, if not, it isdetermined whether the WiFi module 120 and the BT module 130 occupy thetime period for Tx and Rx operations, respectively (step S1415). If so,the control unit 1310 sends control signals to activate the WiFi Txfront-end 151 and the BT Rx front-end 154, switch the balun-switch unit163 to the BT Rx front-end 154, switch the switching device 1320 to theport 1, and switch the switching device 1340 to the port 32 or 38 forthe time period (mode 7) (step S1416), thereby enabling the WiFi Txsignals to be transmitted from the WiFi module 120 via the WiFi Txfront-end 151, the port 1, and the through path between the ports 32 and34 in sequence to the antenna 10, along with the BT Rx signals to bereceived from the antenna 10 by the BT module 130 via the through pathbetween the ports 36 and 38, the port 3, and the BT Rx front-end 154 insequence. Subsequent to step S1415, if not, it is determined whetherboth of the WiFi module 120 and the BT module 130 occupy the time periodfor Tx operations (step S1417). If so, the control unit 1310 sendscontrol signals to activate the WiFi Tx front-end 151 and the BT Txfront-end 155, switch the balun-switch unit 163 to the BT Tx front-end155, switch the switching device 1320 to the port 1, and switch theswitching device 1340 to the port 32 or 38 for the time period (mode 8)(step S1418), thereby enabling the WiFi Tx signals to be transmittedfrom the WiFi module 120 via the WiFi Tx front-end 151, balun 161, theport 1, and the through path between the ports 32 and 34 in sequence tothe antenna 10, along with the BT Tx signals to be transmitted from theBT module 130 via the BT Tx front-end 155, the port 3, and the throughpath between the ports 36 and 38 in sequence to the antenna 10.

Subsequent to step S1410, if not, it is determined whether the WiFimodule 120 and the BT module 130 occupy the time period for Rx and Txoperations, respectively (step S1419). If so, the control unit 1310determines whether a collision has occurred in the traffic requests fromthe WiFi module 120 and the BT module 130, and arbitrates which trafficrequest is to be granted when a collision has occurred (step S1420). Ifthe granted traffic request is from the WiFi module 120, the controlunit 1310 sends control signals to activate the WiFi/BT Rx front-end152, switch the balun-switch unit 162 to the WiFi/BT Rx front-end 152,switch the switching device 1320 to the port 2, and switch the switchingdevice 1340 to the port 32 for the time period (mode 9) (step S1421),thereby enabling the WiFi Rx signals to be received from the antenna 10by the WiFi module 120 via the through path between the ports 32 and 34,the port 2, the WiFi/BT Rx front-end 152, and the separator 140 insequence. If the granted traffic request is from the BT module 130, thecontrol unit 1310 sends control signals to activate the BT Tx front-end153, switch the balun-switch unit 162 to the BT Tx front-end 153, switchthe switching device 1320 to the port 2, and switch the switching device1340 to the port 32 for the time period (mode 9) (step S1422), therebyenabling the BT Tx signals to be transmitted from the BT module 130 viathe BT Tx front-end 153, the port 2, and the through path between theports 32 and 34 in sequence to the antenna 10. Subsequent to step S1419,if not, it is determined whether both of the WiFi module 120 and the BTmodule 130 occupy the time period for Rx operations (step S1423). If so,the control unit 1310 sends control signals to activate the WiFi/BT Rxfront-end 152, switch the balun-switch unit 162 to the WiFi/BT Rxfront-end 152, switch the switching device 1320 to the port 2, andswitch the switching device 1340 to the port 32 for the time period(mode 10) (step S1424), thereby enabling a combined signal to bereceived from the antenna 10 by the separator 140 via the through pathbetween ports 32 and 34, the port 2, and the WiFi/BT Rx front-end 152 insequence. Thereafter, the separator 140 separates them into the WiFi andBT Rx signals and further forwarded to the WiFi module 120 and BT module130, respectively. Subsequent to step S1423, if not, it is determinedwhether the WiFi module 120 and the BT module 130 occupy the time periodfor Tx and Rx operations, respectively (step S1425). If so, the controlunit 1310 determines whether a collision has occurred in the trafficrequests from the WiFi module 120 and the BT module 130, and arbitrateswhich traffic request is to be granted when a collision has occurred(step S1426). If the granted traffic request is from the WiFi module120, the control unit 1310 sends control signals to activate the WiFi Txfront-end 151, switch the switching device 1320 to the port 1, andswitch the switching device 1340 to the port 32 for the time period(mode 11) (step S1427), thereby enabling the WiFi Tx signals to betransmitted from the WiFi module 120 via the WiFi Tx front-end 151,balun 161, the port 1, and the through path between the ports 32 and 34in sequence to the antenna 10. If the granted traffic request is fromthe BT module 130, the control unit 1310 sends control signals toactivate the WiFi/BT Rx front-end 152, switch the balun-switch unit 162to the WiFi/BT Rx front-end 152, switch the switching device 1320 to theport 2, and switch the switching device 1340 to the port 32 for the timeperiod (mode 11) (step S1428), thereby enabling the BT Rx signals to bereceived from the antenna 10 by the BT module 130 via the through pathbetween the ports 32 and 34, the port 2, the WiFi/BT Rx front-end 152,and the separator 140 in sequence. Subsequent to step S1425, if not, itis determined whether both of the WiFi module 120 and the BT module 130occupy the time period for Tx operations (step S1429). If so, thecontrol unit 1310 determines whether a collision has occurred in thetraffic requests from the WiFi module 120 and the BT module 130, andarbitrates which traffic request is to be granted when a collision hasoccurred (step S1430). If the granted traffic request is from the WiFimodule 120, the control unit 1310 sends control signals to activate theWiFi Tx front-end 151, switch the switching device 1320 to the port 1,and switch the switching device 1340 to the port 32 for the time period(mode 12) (step S1431), thereby enabling the WiFi Tx signals to betransmitted from the WiFi module 120 via the WiFi Tx front-end 151,balun 161, the port 1, and the through path between the ports 32 and 34in sequence to the antenna 10. If the granted traffic request is fromthe BT module 130, the control unit 1310 sends control signals toactivate the BT Tx front-end 153, switch the balun-switch unit 162 tothe BT Tx front-end 153, switch the switching device 1320 to the port 2,and switch the switching device 1340 to the port 32 for the time period(mode 12) (step S1432), thereby enabling the BT Tx signals to betransmitted from the BT module 130 via the BT Tx front-end 153, the port2, and the through path between the ports 32 and 34 in sequence to theantenna 10.

Without departing from the spirit of the invention, other embodiments ofa method for the coexistence between the Bluetooth module and theWiMAX/LTE module, or between WiFi module and WiMAX/LTE module, handledby the control unit can be devised with relevant modifications accordingto the architectures in FIGS. 4 and 13, and the control flows in FIGS.12A to 12G and 14A to 14G.

Although the WiFi and BT wireless communication services are used forillustration of the invention, other wireless communication services canbe used, such as Global Positioning System (GPS). FIG. 15 shows anotherembodiment of a system for the coexistence between a Global PositioningSystem (GPS) and a subsystem sharing a single antenna, wherein thesubsystem may be any one of the systems 400 and 1300 excluding theantenna 10. The system 1500 comprises an antenna 10, a diplexer 1510, aGPS module 1520, and a subsystem 1530. The diplexer 1510, which consistsof three terminals 12, 14, and 16, is configured to connect the terminal12 to both terminals 14 and 16 such that the GPS signals (Tx or Rxsignal) are transmitted to/received from the shared antenna 10 via thediplexer 1510, and the wireless signals of the subsystem 1530 (Tx or Rxsignal) are simultaneously transmitted to/received from the sharedantenna 10 via the diplexer 1510.

While the invention has been described by way of example and in terms ofthe preferred embodiments, it is to be understood that the invention isnot limited to the disclosed embodiments. To the contrary, it isintended to cover various modifications and similar arrangements (aswould be apparent to those skilled in the art). Therefore, the scope ofthe appended claims should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

What is claimed is:
 1. A wireless communications system, comprising: afirst wireless communications module configured to transmit or receive afirst wireless signal in a first frequency band selected from a firstfrequency range; and a second wireless communications module configuredto transmit or receive a second wireless signal in a second frequencyband selected from a second frequency range which overlaps at least inpart with the first frequency range; wherein the first wirelesscommunications module is further configured to determine an in-bandrange in the overlapping part of the first and second frequency ranges,wherein the in-band range corresponds to a frequency range where areceived first wireless signal and a received second wireless signalexperience in-band interference caused by a transmitted second wirelesssignal and a transmitted first wireless signal, respectively; andwherein a transmission power of the second wireless signal is adjustedin response to a frequency offset between the first frequency band andthe second frequency band falling within the in-band range.
 2. Thewireless communications system as claimed in claim 1, wherein theadjustment of the transmission power of the second wireless signalcomprises decreasing the transmission power of the second wirelesssignal when the frequency offset between the first frequency band andthe second frequency band is less than or equal to a predeterminedthreshold.
 3. The wireless communications system as claimed in claim 2,wherein the decreased transmission power of the second wireless signalmeets a requirement so that the first wireless signal can be received bythe first wireless communications module in concurrence withtransmission of the second wireless signal by the second wirelesscommunications module.
 4. The wireless communications system as claimedin claim 1, wherein the second frequency range comprises a plurality ofhopping channels, and the adjustment of the transmission power of thesecond wireless signal is performed when a frequency offset between anext hopping channel of the second wireless signal and the firstfrequency band is within the predetermined range.
 5. The wirelesscommunications system as claimed in claim 1, wherein the first frequencyrange comprises a plurality of hopping channels, and the adjustment ofthe transmission power of the second wireless signal is performed when afrequency offset between the second frequency band of the secondwireless signal and a next hopping channel of the first wireless signalis within the predetermined range.
 6. The wireless communications systemas claimed in claim 1, wherein the transmission power of the secondwireless signal is adjusted according to at least the frequency offsetbetween the first wireless signal and the second wireless signal,transceiving modulation types, or a signal indicator of the firstwireless signal or the second wireless signal.
 7. The wirelesscommunications system as claimed in claim 6, wherein the signalindicator includes received signal strength indications (RSSI), signalto noise ratios (SNR), adjacent channel interferences (ACI), packeterror rates (PER), or bit error rates (BER).
 8. The wirelesscommunications system as claimed in claim 5, wherein one of the firstand second wireless communication modules determines a channel mapdescribing information of the in-band range of the first or secondwireless signal, and sends the channel map and its transceivingmodulation type to the other.
 9. A method for reducing interferencebetween a plurality of wireless communications modules in a wirelesscommunications device, comprising: transmitting or receiving a firstwireless signal in a first frequency band selected from a firstfrequency range by a first wireless communications module, andtransmitting or receiving a second wireless signal in a second frequencyband selected from a second frequency range, which overlaps at least inpart with the first frequency range, by a second wireless communicationsmodule; determining an in-band range in the overlapping part of thefirst and second frequency ranges, wherein the in-band range correspondsto a frequency range where a received first wireless signal and areceived second wireless signal experience in-band interference causedby a transmitted second wireless signal and a transmitted first wirelesssignal, respectively; and adjusting a transmission power of the secondwireless signal in response to a frequency offset between the firstfrequency band and the second frequency band falling within the in-bandrange.
 10. The method as claimed in claim 9, wherein the adjustment ofthe transmission power of the second wireless signal comprisesdecreasing the transmission power of the second wireless signal when thefrequency offset between the first frequency band and the secondfrequency band is less than or equal to a predetermined threshold. 11.The method as claimed in claim 10, wherein the decreased transmissionpower of the second wireless signal meets a requirement so that thefirst wireless signal can be received by the first wirelesscommunications module in concurrence with transmission of the secondwireless signal by the second wireless communications module.
 12. Themethod as claimed in claim 9, wherein the second frequency rangecomprises a plurality of hopping channels, and the adjustment of thetransmission power of the second wireless signal is performed when afrequency offset between a next hopping channel of the second wirelesssignal and the first frequency band is within the predetermined range.13. The system as claimed in claim 9, wherein the transmission power ofthe second wireless signal is adjusted according to the frequency offsetbetween the first wireless signal and the second wireless signal,transceiving modulation types, or a signal indicator of the firstwireless signals or the second wireless signals.
 14. The system asclaimed in claim 13, wherein the signal indicator includes receivedsignal strength indications (RSSI), signal to noise ratios (SNR),adjacent channel interferences (ACI), packet error rates (PER), or biterror rates (BER).